(ChemotherapyAdvisor) – Surgery alone is curative for most asymptomatic patients with low-risk neuroblastoma, with chemotherapy restricted to specific situations, according to results of Children’s Oncology Group Study P9641 in the Journal of Clinical Oncology online April 23.

The primary study objective was to demonstrate that surgery alone would achieve 3-year overall survival ≥95% for patients with asymptomatic International Neuroblastoma Staging System stages 2a and 2b neuroblastoma, the investigators noted.

Each patient had a maximally safe tumor resection. Chemotherapy was reserved for those with—or at risk for—symptomatic disease, with <50% tumor resection at diagnosis, or with unresectable progressive disease after surgery alone.

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For the 915 eligible patients, 5-year event-free survival was 89% ± 1% and overall survival was 97% ± 1%. For those with asymptomatic stage 2a or 2b disease, 5-year event-free survival was 87% ± 2% and overall survival was 96% ± 1%.

Among patients with stage 2b disease, event-free survival and overall survival were significantly lower for those with unfavorable histology or diploid tumors, and overall survival was significantly lower for those ≥18 months old. For patients with stage 1 neuroblastoma, 5-year overall survival rates were 99% ± 1% and, for stage 4s, 91% ± 1%. Five-year overall survival for patients who required chemotherapy at diagnosis was 98% ± 1%. Of all patients observed after surgery, 11.1% experienced recurrence or progression of disease.

“Excellent survival rates can be achieved in asymptomatic low-risk patients with stages 2a and 2b neuroblastoma after surgery alone,” the investigators wrote. “Children with MYCN-A stage 1 neuroblastoma and those with MYCN-NA stage 2b neuroblastoma who are ≥18 months of age or who have unfavorable histology or diploid disease have a less favorable outcome than other low-risk patients. Further refinements of risk classification schema are needed for these patients. These refinements, further restriction of chemotherapy, and questions about the extent of surgical resection necessary for cure will be the goals of future studies.”